Chambers tested positive for THG (tetrahydrogestrinone) on 1 August 2003.

Not only was he banned for two years on 7 November that year, he was also subsequently stripped of the 4x100m relay silver medal he won at the 2003 World Championships.

Under British Olympic Association rules, he will not be allowed to compete at a future Olympic Games either.

But it could get even worse for the 27-year-old Londoner before it gets better.

He could also lose the individual and relay gold medals he won at the 2002 European Championships as well as his British record of 9.87 seconds, set in September later that year.

That is because he has also revealed to BBC Sport that he was taking THG a full 18 months before he was caught.

Chambers is philosophical about the possibility of losing more accolades.

"There's nothing I can do about it," he said.

"I've come to terms with what has happened and I'm blessed that I have the opportunity to come back and make amends.

"I don't believe THG had anything to do with the fact that I ran 9.87 seconds.

"That came about because I was in a world record race and was dragged along."

Chambers started taking THG after switching his training base to California at the start of 2002.

There he worked with veteran coach Remi Korchemny, who introduced him to Victor Conte, a self-made nutritional expert and founder of the pharmaceutical company Balco.

It was Conte who supplied Chambers with THG.

"I took THG, but I didn't know what its gains and benefits were," said the Briton.

"THG came in liquid form and you put a few drops under your tongue three to four times a week.

"I was a bit suspicious about why you would put it under your tongue, but Victor explained it was a new product on the market that would aid me nutritionally, so I went forward with it.

"Nutrition wasn't something I was interested in, so when he was explaining all this scientific jargon to me about THG and various other supplements, it came in one ear and fell out of the other.

"In hindsight I was very foolish not to ask certain questions about THG, but no-one had ever heard of it before so I didn't see any reason to question it.

"But there's nobody else I can blame, for the simple reason that I made those decisions to go forward as I did.

"Despite my suspicions, I still went forward and did it."

Conte also supplied Kelli White, the double world sprint champion who, like Chambers, was also handed a two-year doping ban.

And Conte himself is now serving a four-month prison sentence for his role in a scheme to give athletes undetectable performance-enhancing drugs.

As for Chambers, he is now focusing on a return to the track after a short-lived and unsuccessful attempt to forge a career in American Football.

He will be free to compete again when he has taken and passed three new dope tests - which is expected to happen by the end of January.

He has been training in Jamaica with Glen Mills, coach to Kim Collins - the man who beat him to Commonwealth 100m gold in 2002 and the world title a year later.

Both athlete and coach say they are very pleased with the progress made, and as a result Chambers will try to make the British team for March's World Indoor championships.

With selection for March's Commonwealth Games already decided, the obvious target after that is the defence of his European crown in Gothenburg, Sweden, in August.

"Mentally I'm fine now but I'm not sure how my body's going to cope when I get back on the track," said Chambers.

"I miss competing and that's made me determined to come back and have fun on the track again."

And he added: "I need to get some money back in my pocket because I'm broke. I have to earn a living."

He is also keen to make amends to the people he let down, particularly Marlon Devonish, Christian Malcolm and Darren Campbell, who also lost their relay silver medals because of his drugs taking.

"If there's an opportunity for me to make it up to them, I want to take it," said Chambers.